Apparatus and method to switch configurable logic units

ABSTRACT

Examples described herein include systems and methods which include an apparatus comprising a plurality of configurable logic units and a plurality of switches, with each switch being coupled to at least one configurable logic unit of the plurality of configurable logic units. The apparatus further includes an instruction register configured to provide respective switch instructions of a plurality of switch instructions to each switch based on a computation to be implemented among the plurality of configurable logic units. For example, the switch instructions may include allocating the plurality of configurable logic units to perform the computation and activating an input of the switch and an output of the switch to couple at least a first configurable logic unit and a second configurable logic unit. In various embodiments, configurable logic units can include arithmetic logic units (ALUs), bit manipulation units (BMUs), and multiplier-accumulator units (MACs).

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No. 15/493,551 filed Apr. 21, 2017 and issued as U.S. Pat. No. 10,963,265 on Mar. 30, 2021. The aforementioned application, and issued patent, is incorporated herein by reference, in its entirety, for any purpose.

BACKGROUND

Many processing architectures exist to accomplish digital signal processing (DSP) capabilities, such as adders, multipliers, and other arithmetic logic units (ALUs) utilized in combination. For example, digital signal processing for wireless communications, such as digital baseband processing or digital front-end implementations, may be implemented using hardware (e.g. silicon) computing platforms. Multimedia processing and digital radio frequency (RF) processing may be implemented using an application-specific integrated circuit (ASIC). Accordingly, a variety of hardware platforms are available to implement digital signal processing, such as the ASIC, a digital signal processor (DSP) implemented as part of a field-programmable gate array (FPGA), or a system-on-chip (SoC). However, each of these solutions often requires implementing customized signal processing methods that are hardware-implementation specific. Such architectures, custom-built, may not be able to (or not efficiently able to) implement other applications that were not designed specifically for that hardware architecture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 are block diagrams of an example integrated circuit in accordance with embodiments of the present disclosure.

FIG. 3 is a block diagram of an example FPGA in accordance with an embodiment of the present disclosure.

FIG. 4 is a flow diagram of an example method of switching configurable logic units (CLUs) according to an embodiment of the disclosure.

FIG. 5 is a schematic illustration of system arranged in accordance with examples described herein.

DETAILED DESCRIPTION

Certain details are set forth below to provide a sufficient understanding of embodiments of the present disclosure. However, it will be clear to one skilled in the art that embodiments of the present disclosure may be practiced without various of these particular details. In some instances, well-known wireless communication components, circuits, control signals, timing protocols, computing system components, and software operations have not been shown in detail in order to avoid unnecessarily obscuring the described embodiments of the present disclosure.

Example systems and methods described herein include integrated circuits, such as an FPGA, that provide switch instructions to various switches based on a computation to be implemented among a plurality of configurable logic units coupled to inputs and outputs of the switches. Providing switch instructions in such a way may allow an efficient allocation of configurable logic units in an integrated circuit, and can improve processing time of computations that may involve iterative or repetitive computation. For example, such switch instructions may improve the processing time of wireless communications processing, DSP operations, machine learning, tensor processing, matrix operations, or artificial intelligence operations; for example, for such operations and/or processing to be performed more efficiently through an efficient allocation of configurable logic units for respective processing tasks. For example, if the computation to be implemented is a Fast Fourier Transform (FFT), a routing path through a portion of the plurality of configurable logic units may be selected to achieve an arrangement of, for example an arithmetic logic unit (ALU) and a multiplier-accumulator unit (MAC), which may compute an inverse square root operation associated with the FFT or QR decomposition. QR decompositions may be used, for example, to decompose a matrix A into a product of an orthogonal matrix Q and an upper triangular matrix R. QR decomposition may be used, for example, in solving least squares problems. In some current implementations of an FPGA architecture, a DSP unit process such an inverse square root operation may be implemented in a specific circuit specially configured for such a computation. For example, a programmer may configure specific circuitry in a specific portion of the FPGA to configure the FPGA to perform such a computation when called by an operation, like an FFT operation. However, such configurations (which may be by pre-design) do not allow the flexibility of an FPGA framework to dynamically reallocate the couplings of configurable logic units or determine routing paths, when called, for example, by an operation in-process at the FPGA. Accordingly, it may be advantageous to provide an integrated circuit (e.g., a programmable logic device (PLD)) that can activate the input and outputs of respective switches within that integrated circuit, to form routing paths for a computation to be implemented among the plurality of configurable logic units. For example, the computation may be dynamically called during a process or circuit implemented at the integrated circuit.

Additionally, some operations may include iterative processing of a computation (e.g. repeated use of an operation). For example, an inverse square root operation of an FFT or QR decomposition process may include iterative processing, such that the iterative processing increases the precision of the solution to the inverse square root computation. Iterative processing in such a square root operation may also facilitate an efficient solution to the inverse square operation. Accordingly, it may be advantageous to provide an integrated circuit (e.g., a programmable logic device (PLD)) that can activate the input and outputs of respective switches within that integrated circuit, such that an iterative computation may be performed utilizing the coupled configurable logic units of those activated inputs and outputs. Such an integrated circuit, as described herein, may also include switch instructions that specify a number of iterations for the computation to be performed iteratively; for example, when an input for that operation is received at a switch. The iterative processing may be facilitated by a direct coupling between the initial switch receiving the input, and a final switch that provides feedback (e.g., an intermediate processing result) to the initial switch.

FIG. 1 is a block diagram of an example integrated circuit 100 in accordance with embodiments of the present disclosure. The example integrated circuit 100 includes at least one configurable logic block 105. The configurable logic block 105 may include an arrangement of circuit elements or a single circuit that performs operations, as a part of the integrated circuit 100. In some embodiments, the configurable logic block 105 may implement various functionalities for the integrated circuit, such as computation processing for various operations of wireless communications processing, DSP operations, machine learning applications, tensor processing, matrix operations, or artificial intelligence operations. The configurable logic block 105 may be configured to implement a specific computation or sub-computation of an operation executing on the integrated circuit 100. As depicted in FIG. 1, the configurable logic block 105 may include an input port for an input path 107 coupled to the configurable logic block 105 via an input of the switch 110 a. The configurable logic block 105 may include an output port for an output path 140 coupled to the configurable logic block 105 via an output of the switch 140. The integrated circuit 100 may provide input paths 107 to the configurable logic block 105 for processing of an operation executing on the integrated circuit 100. Output paths 140 may be provided from the configurable logic block 105, which may provide data upon completion of the processing by configurable logic block 105. The input path 107 may receive one or more operands for processing in the configurable logic block 105. The output path 140 may provide one more operands for further processing via a feedback line 142 of the configurable logic block 105 or for an input to the operation executing on the integrated circuit 100. Such input paths 107 and output paths 140 may facilitate processing of operations executing in the integrated circuit 100; for example by utilizing the efficient allocation of logic units 120 a-120 c, 130 a-130 c in the configurable logic block 105.

The configurable logic block 105 includes switches 110 a-110 c and logic units 120 a-120 c, 130 a-130 c. As depicted, inputs and outputs of the switches 110 a-110 c are coupled to various respective outputs and inputs of the logic units 120 a-120 c, 130 a-130 c. For example, a first output of switch 110 a is coupled to an input of the ALU 120 a; a second output of the switch 110 a is coupled to the input of the MAC 120 b; and a third output of the switch 110 a is coupled to the input of the bit manipulation unit (BMU) 120 c. Continuing in the example, an output of the ALU 120 a is coupled to a first input of the switch 110 b; and output of the MAC 120 b is coupled to a second input of the switch 110 b; and an output of the BMU 130 c is coupled to a third input of the switch 110 b. As another example, the first output of switch 110 b is coupled to an input of the ALU 130 a; a second output of the switch 110 b is coupled to the input of the MAC 130 b; and a third output of the switch 110 b is coupled to the input of the BMU 130 c. Continuing in this example, an output of the ALU 130 a is coupled to a first input of the switch 110 c: and output of the MAC 130 b is coupled to a second input of the switch 110 c; and an output of the BMU 130 c is coupled to a third input of the switch 110 c.

Generally described, the ALU 120 a, 130 b, the MAC 120 b, 130 b, and BMU 120 c, 130 c may be an implementation of a configurable logic unit (CLU). A configurable logic unit may perform a variety of arithmetic, matrix, tensor, and/or DSP operations. A CLU may be an arrangement of circuit elements or a single circuit that performs such an operation. A CLU may be used to implement an adder unit (e.g., the ALUs 120 a, 130 b), a multiplier unit, an accumulator unit, a multiply-accumulate unit (e.g., the MACs 120 b, 130 b), a carry-in unit, a carry-out unit, a bit shifter, a logic unit configured with NAND gates, and/or generally any type of arithmetic logic unit or DSP logic unit that may process DSP operations. One or more CLUs may work combination to receive and process operands via input and output ports of those respective CLUs.

The ALUs 120 a, 130 b may be a specific implementation of a configurable logic unit. The ALUs 120 a, 130 b may receive one or more operands from the respective switches 110 a, 110 b for an addition operation. For example, the ALU 120 a may receive an operand from the switch 110 a to add with another operand. The other operand may also be received from the switch 110 a; or, in some implementations, the other operand may be retrieved from a register of the ALU 120 a or a look-up table of the configurable logic block 105. The ALU 120 a outputs the addition processing result to the switch 110 b.

The MACs 120 b, 130 b may be a specific implementation of a configurable logic unit. The MACs 120 b, 130 b may receive one or more operands from the respective switches 110 a, 110 b for an addition operation. For example, the MAC 120 b may receive an operand from the switch 110 a to multiply and accumulate with other operands. In the example, the MAC 120 b may perform a multiply-accumulate operation such that two operands, A and B, are multiplied and then added with C to generate a new version of C that is the output of the MAC 120 b. The other operands may also be received from the switch 110 a; or, in some implementations, the other operand may be retrieved from a register of the MAC 120 b or a look-up table of the configurable logic block 105. The MAC 120 b outputs the multiply-accumulation processing result to the switch 110 b.

The BMUs 120 c, 130 c may be a specific implementation of a configurable logic unit. The BMUs 120 c, 130 c may receive one or more operands from the respective switches 110 a, 110 b for a bit manipulation operation. Bit manipulation operations may include manipulations on one or more bits of the operand. Such bit manipulations may include setting a bit, clearing a bit, toggling a bit, testing a bit, shifting a bit, or performing a bitwise operation on a bit. Bitwise operations may include AND, OR, XOR, or NOT logical operations on a bit. For example, the BMU 120 a may receive an operand from the switch 110 a to alter a bit of that operand. In the example, the BMU 120 a may perform setting one or more bits of the operand, such that the operand is set to a zero vector (e.g., setting all bits to zero) or a unity vector (e.g., setting all bits to one). The BMU 120 a outputs the bit manipulation processing result to the switch 110 b.

The configurable logic block 105 also includes the instruction register 150 that is configured to provide respective switch instructions to each switch 110 a-110 c based on a computation to be implemented among at least some of the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c. The instruction register 150 may receive such instructions (or instructions representative of the switch instructions) to perform the computation from the integrated circuit 100. The instruction register 150 may receive such instructions, for example, from an interconnect coupled to the configurable logic block 105 (such as the interconnect 302 coupling configurable logic blocks 305 a-305 f in FIG. 3). The instruction register 150 in some examples may receive a computation mode selection from an operation execution on the integrated circuit 100 or a user interacting with the integrated circuit 100. A computation mode selection may indicate a specific computation mode for the configurable logic block 105. The switch instructions may utilize a computation mode selection to allocate respective the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c of the configurable logic block 105 for processing of data from an input data path 107 to generate data provided to an output data path 140 or feedback 142. The computation mode may be implemented using the instruction register 150 that may store a mode indicator based on the computation to be implemented among the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c. The computation mode of the configurable logic block 105 can be utilized by the instruction register 150 to determine a routing path among the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c for the computation to be implemented. The instruction register 150 may identify an availability status of each of the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c. For example, the ALU 130 a may not be available if it is performing a computation for another process executing on the configurable logic block 105. The ALU 120 a may be available if it is not performing a computation or is not scheduled to execute a computation on the configurable logic block 105.

The instruction register 150 may allocate certain tasks among the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c for the computation to be implemented. In some examples, execution of the switch instructions may include allocation of the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c to operate according to the computation mode. Execution of the switch instructions may include providing selection signals to the switches 110 a-110 c to specify which inputs and outputs are activated of the respective switches for that specific computation. For example, if the computation to be implemented is an inverse square root operation, which may be associated with an FFT operation or QR decomposition, a routing path through the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c may be determined to perform the inverse square root operation. Accordingly, the switch instructions may provide selection signals that may activate respective inputs and outputs for the configurable logic block 105 to implement this computation. In the example of the inverse square root operation, such switch instructions may include a selection signal that indicates the first output of switch 110 a that is coupled to an input of the ALU 120 a is to be activated; and another selection signal that indicates the output of the ALU 120 a that is coupled to a first input of the switch 110 b is to be activated. For example, such selection signals may be provided to the switches 110 a, 110 b from the instruction register 150. The switch instructions may further include a selection signal that may indicate the second output of the switch 110 b is to be coupled to the input of the MAC 130 b is to be activated; and another selection signal that indicates the output of the MAC 130 b that is coupled to a second input of the switch 110 c is to be activated. For example, such selection signals may be provided to the respective switches 110 b, 110 c from the instruction register 150.

As another example of allocation among the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c by the instruction register 150, if the computation to be implemented is a Galois-Field division, a routing path through the ALUSs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c may be provided which implements all or a portion of Galois-Field division. For example, the switch instructions may provide selection signals that activate respective inputs and outputs for the configurable logic block 105 to implement Galois-Field division. Such switch instructions may include a selection signal that indicates the first output of switch 110 a that is coupled to an input of the ALU 120 a is to be activated; and another selection signal that indicates the output of the ALU 120 a that is coupled to a first input of the switch 110 b is to be activated. For example, such selection signals may be provided to the switches 110 a, 110 b from the instruction register 150. The switch instructions may further include a selection signal that indicates the third output of the switch 110 b that is coupled to the input of the BMU 130 c is to be activated; and another selection signal that indicates the output of the BMU 130 that is coupled to a third input of the switch 110 c is activated. For example, such selection signals may be provided to the respective switches 110 b, 110 c from the instruction register 150.

In providing the switch instructions, the instruction register 150 may also include an indication of a number of iterations to be performed through the portion of the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c allocated to perform the computation. In various embodiments, the number of iterations may be specified in the computation mode selection received at the instruction register 150. The number of iterations may be based on that computation to be implemented among the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c. In iterating, the configurable logic block 105 may utilize the feedback line 142 to provide an intermediate processing result from a final configurable logic unit of a determined routing path back to an initial configurable logic unit of that same determined routing path for that computation mode.

In some examples, execution of the switch instructions may include providing a selection signal including the number of iterations to operate according to the specified iterations for that computation. Execution of the switch instructions may include providing selection signals to the switches 110 a-110 c to specify how many executions of operands are to be scheduled for the allocated portion of the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c. For example, if the computation to be implemented is an inverse square root operation, switch instructions may include a selection signal that indicates the number of iterations an operand is to be provided to the first output of switch 110 a that is coupled to an input of the ALU 120 a; and another selection signal that indicates the number of iterations an operand is to be received from the output of the ALU 120 a that is coupled to a first input of the switch 110 b. For example, such selection signals may be provided to the switches 110 a, 110 b from the instruction register 150. The switch instructions may further include a selection signal that indicate the same number of iterations an operand is to be provided to the second output of the switch 110 b that is coupled to the input of the MAC 130 b; and another selection signal that indicates the same number of iterations an operand is to be received from the output of the MAC 130 b that is coupled to a second input of the switch 110 c. For example, such selection signals may be provided to the respective switches 110 b, 110 c from the instruction register 150. In some examples, the number of iterations through such a routing may be 3, 10, 128, 256, or 512 iterations. In iterating, the configurable logic block 105 may utilize the feedback line 142 to provide an intermediate processing result from the MAC 130 b via the switch 110 c back to the ALU 120 a via the feedback line. The number of iterations may specify the number of iterations that the feedback line is utilized.

As another example of providing a number of iterations in the switch instructions, if the computation to be implemented is a Galois-Field operation, such as multiplication, switch instructions may include a selection signal that indicates the number of iterations an operand is to be provided to the first output of switch 110 a that is coupled to an input of the ALU 120 a; and another selection signal that indicates the number of iterations an operand is to be received from the output of the ALU 120 a that is coupled to a first input of the switch 110 b. For example, such selection signals may be provided to the switches 110 a, 110 b from the instruction register 150. The switch instructions may further include a selection signal that indicate the same number of iterations an operand is to be provided to the third output of the switch 110 b that is coupled to the input of the BMU 130 c; and another selection signal that indicates the same number of iterations an operand is to be received from the output of the BMU 130 that is coupled to the third input of the switch 110 c. For example, such selection signals may be provided to the respective switches 110 b, 110 c from the instruction register 150. In some examples, the number of iterations through such a routing may be 2, 10, 128, 256, or 512 iterations. In iterating, the configurable logic block 105 may utilize the feedback line 142 to provide an intermediate processing result from the BMU 130 c via the switch 110 c back to the ALU 120 a via the feedback line.

Advantageously, the integrated circuit 100 of FIG. 1 may activate the inputs and outputs of respective switches within that integrated circuit, to form routing paths for a computation to be implemented among the ALUs 120 a, 130 a, MACs 120 b, 130 b, and the BMUs 120 c, 130 c. Accordingly, the computation may be dynamically called during a process or circuit implemented at the integrated circuit 100, with the switch instructions providing selection signals to the switches 110 a-110 c to implement the computation in the configurable logic block 105. While described in the context of an integrated circuit, it can be appreciated that the configurable logic block 105 may be included in any hardware platform, such as an ASIC, an FPGA, or a SoC.

FIG. 2 is a block diagram of an example integrated circuit 200 in accordance with embodiments of the present disclosure. The example integrated circuit 200 includes at least one configurable logic block 205. Similarly numbered elements of FIG. 2 include analogous functionality to those numbered elements of FIG. 1. For example, the instruction register 250 may operate and be configured like the instruction register 150 of FIG. 1. The configurable logic block 205 includes the CLUs 220 a-c, 230 a-c. As described herein, a configurable logic unit, such as CLUs 220 a-c, 230 a-c, may perform a variety of arithmetic, matrix, tensor, or DSP operations. Any of the CLUs 220 a-c, 230 a-c, may be used to implement an adder unit (e.g., like the ALUs 120 a, 130 b), a multiplier unit, an accumulator unit, a multiply-accumulate unit (e.g., like the MACs 120 b, 130 b), a carry-in unit, a carry-out unit, a bit shifter, a bit manipulation unit (e.g., like the BMUs 120 c, 130 c), a logic unit configured with NAND gates, and/or generally any type of arithmetic logic unit or DSP logic unit that may process DSP operations.

The instruction register 250 may provide respective switch instructions to each switch 210 a-210 c according to a computation to be implemented among at least some of the CLUs 220 a-c, 230 a-c. The instruction register 250 may receive such instructions (or instructions representative of the switch instructions) to perform the computation from the integrated circuit 200. The instruction register 250 may receive such instructions, for example, from an interconnect coupled to the configurable logic block 205 (such as the interconnect 302 coupling configurable logic blocks 305 a-305 f in FIG. 3). The instruction register 250 some examples, may receive a computation mode selection, for example, a computation mode selection from an operation execution on the integrated circuit 200 or a user interacting with the integrated circuit 200. A computation mode selection can indicate specific computation mode for the configurable logic block 205. The switch instructions may utilize a computation mode selection to allocate respective the CLUs 220 a-c, 230 a-c of the configurable logic block 205 for processing of an input data path 207 to generate an output data path 240 or feedback 242. The computation mode may be implemented using the instruction register 250 that stores a mode indicator based on the computation to be implemented among the CLUs 220 a-c, 230 a-c. The computation mode of the configurable logic block 205 can be utilized by the instruction register 250 to determine a routing path among the CLUs 220 a-c, 230 a-c for the computation to be implemented.

Execution of the switch instructions may include providing selection signals to the switches 210 a-210 c to specify which inputs and outputs are activated of the respective switches for that specific computation. For example, a computation may include at least an addition operation and a multiplication operation. The addition operation and multiplication operation may be referred to as sub-computations of the computation. A routing path through the CLUs 220 a-c, 230 a-c may be determined to be an allocation of the CLU 220 b and the CLU 230 b to perform the respective addition and multiplication operations. Accordingly, the switch instructions may provide selection signals that activate respective inputs and outputs for the configurable logic block 205 to implement this computation. In the example of computation including the addition and multiplication operation, such switch instructions may include a selection signal that indicates a second output of switch 210 a that is coupled to an input of the CLU 220 b is to be activated; and another selection signal that indicates the output of the CLU 220 b that is coupled to a second input of the switch 210 b is to be activated. For example, such selection signals may be provided to the switches 210 a, 210 b from the instruction register 250. The switch instructions may further include a selection signal that indicate the second output of the switch 210 b that is coupled to the input of the CLU 220 c is to be activated; and another selection signal that indicates the output of the CLU 220 c that is coupled to a second input of the switch 110 c is to be activated. For example, such selection signals may be provided to the respective switches 110 b, 110 c from the instruction register 150. In various embodiments, input and outputs may be utilized of the switches 210 a-210 c from whichever inputs and outputs are not currently activated. A selection signal may also indicate that another output or input of a switch is to be utilized rather than a path that has been activated. Accordingly, in the example of the depicted path of the output of the CLU 220 c that is coupled to a second input of the switch 110 c, a selection signal may, instead, indicate that the output of the CLU 220 c is be coupled to a third input of the switch 110 c.

The instruction register 250 may provide respective switch instructions to each switch 210 a-210 c that configure at least some of the CLUs 220 a-c, 230 a-c to perform a specific sub-computation of the computation to be implemented among the CLUs 220 a-c, 230 a-c. For example, a first CLU 220 a may receive instructions from the switch to be configured as an adder unit that adds an operand to be received from the switch 210 a to another operand. The other operands may also be received from the switch 110 a; or, in some implementations, the other operand may be retrieved from a register of the CLU 220 a or a look-up table of the configurable logic block 205. The second CLU 220 b may receive instructions from the switch to be configured as a multiplier unit that multiplies the result of an addition operation from the first CLU 220 a, received via the activated second input and second output of the switch 210 b, with the another operand.

In providing the switch instructions, the instruction register 250 may also include an indication of a number of iterations to be performed through the portion of the CLUs 220 a-c, 230 a-c allocated to perform the computation. In various embodiments, the number of iterations may be specified in the computation mode selection received at the instruction register 250. The number of iterations may be based on that computation to be implemented among the CLUs 220 a-c, 230 a-c. In iterating, the configurable logic block 205 may utilize the feedback line 242 to provide an intermediate processing result from a final configurable logic unit of a determined routing path back to an initial configurable logic unit of that same determined routing path for that computation mode.

While described in the context of examples of a computation including an addition and multiplication sub-computations, it can be appreciated that the CLUs 220 a-c, 230 a-c may perform a variety of computations, with sub-computations to be implemented among the CLUs 220 a-c, 230 a-c to perform the computation. Such computations may include an inverse square root operation, a Galois-Field division, a Galois-Field multiplication, or any other computations performed in integrated circuits for the execution of wireless communications processing, DSP operations, machine learning, tensor processing, matrix operations, or artificial intelligence operations. Such operations and/or processing may be performed more efficiently through an efficient allocation of CLUs 220 a-c, 230 a-c for a processing task. While FIG. 2 depicts two columns of CLUs 220 a-c, 230 a-c and three switches 110 a-110 c, it can be appreciated that any number of columns of CLUs 220 a-c, 230 a- and any number of switches 110 a-110 c may be included in the configurable logic block 205; for example, as physical space on the integrated circuit 200 allows.

FIG. 3 is a block diagram of an example FPGA 300 in accordance with an embodiment of the present disclosure. Example FPGA 300 is an example of an integrated circuit having configurable logic blocks, such as configurable logic blocks 105 or configurable logic blocks 205. The FPGA 300 includes an interconnect 302, with configurable logic blocks 305 a-305 f and I/O blocks 310 a-310 j coupled thereto. While only eight configurable logic blocks 305 a-305 f and ten I/O blocks 310 a-310 j are depicted in FIG. 3, it can be appreciated that FPGA 300 may include any number of configurable logic blocks and I/O blocks 310 a-310 j. The FPGA 300 may cascade configurable logic blocks 305 a-305 f together such that a configurable logic block 305 a-305 f may provide at least one output path as at least one input path to another configurable logic block. A configurable logic block 305 a-305 f may be implemented using be a programmable logic block, such as a computer readable medium storing instructions, or a logic circuit comprising one or more logic units, such as one or more NAND gates. The configurable logic blocks 305 a-305 f may be cascaded across logical rows and columns with I/O blocks 310 a-310 j bounding respective rows and columns for connections external to the FPGA 300. The configurable logic blocks 305 a-305 f may implement configurable logic block that performs various computations, such as the configurable logic block 105 or 205. Certain configurable logic blocks 305 a-305 f configured to operate as the configurable logic blocks 105 or 205 may be logically analogous or similar circuits that are cascaded in the FPGA 300 to perform a single or multiple computations. The computations performed by the configurable logic block 105 or 205 may change individually or in combination. In one implementation, the FPGA 300 may include a number of configurable logic blocks 305 a-305 f, implemented as the configurable logic block 105 or 205, to perform an inverse square root operation.

FIG. 4 is a flowchart of a method 400 in accordance with examples described herein. Example method 400 may be implemented using, for example, the integrated circuit 100 in FIG. 1, or any system or combination of the systems depicted in FIGS. 1-3 and/or described herein. The operations described in blocks 408-424 may be stored as control instructions in a computer-readable medium of or coupled to an integrated circuit (e.g., the integrated circuit 100) or a memory accessible by the integrated circuit.

Example method 400 may begin the switching CLU method. The method 400 may include a block 408 that recites “allocate at least two configurable logic units to perform a computation.” An instruction register may receive a computation mode selection that indicates a specific computation mode for a configurable logic block. The switch instructions may utilize the computation mode selection to allocate respective CLUs of the configurable logic block for processing of input data to generate output data and/or feedback. The instruction register may identify an availability status of each of the CLUs. For example, a CLU may not be available if it is performing a computation for another process executing on the configurable logic block. The CLU may be available if it is not performing a computation or is not scheduled to execute a computation on the configurable logic block. Block 408 may be followed by block 412 that recites “configure each of the at least two configurable logic units to perform a specific sub-computation.” As depicted with a dotted line from block 408 to block 412, block 412 may be an optional step. An instruction register may be configured to provide respective switch instructions to some switches of a configurable logic block that configure at least some of the CLUs to perform a specific sub-computation of the computation to be implemented among the CLUs. For example, a first CLU may receive instructions from the switch to be configured as a CLU with a specific functionality available to that CLU, and a second CLU may receive instructions from another switch to be configured as a CLU with a specific functionality available to that CLU or as a CLU that facilitates the functionality of the first CLU.

Block 412 may be followed by block 416 that recites “determine a routing path through the at least two configurable logic units via at least one switch.” Once availability statuses have been identified, the instruction register may determine a routing path among the CLUs for the computation to be implemented. For example, a computation mode selection can indicate a number of functionalities to be performed by the CLUs and a number of CLUs to perform the computation based on those functionalities. The computation mode selection may also indicate a number of iterations to be performed to compute a final processing result for the computation. The instruction register may utilize such information to determine a routing path among the CLUs based at least on the computation or an availability status of CLUs in a configurable logic block. Block 416 may be followed by block 420 that recites “provide switch instructions to the at least one switch to activate an input and output of the at least one switch.” The instruction register may provide switch instructions that include selection signals that activate respective inputs and outputs of switches to implement the computation. The instruction register may provide switch instructions that include an indication of a number of iterations to be performed through the portion of the CLUs allocated to perform the computation. A selection signal of the switch instructions may also indicate that another output or input of a switch is to be utilized rather than a coupling that has been activated. Block 420 may be followed by block 424 that may end the method 400.

The blocks included in the described example methods 400 are for illustration purposes. In some embodiments, the blocks may be performed in a different order. In some other embodiments, various blocks may be eliminated. In still other embodiments, various blocks may be divided into additional blocks, supplemented with other blocks, or combined together into fewer blocks. Other variations of these specific blocks are contemplated, including changes in the order of the blocks, changes in the content of the blocks being split or combined into other blocks, etc.

FIG. 5 is a schematic illustration of system arranged in accordance with examples described herein. The system 506 includes processing unit(s) 508, which may include integrated circuit with configurable logic block(s) 502 and switch instructions 504. The system 506 may also include operating system 510, application(s) 512, and/or instruction generator 514 which may include executable instructions stored on one or more electronic storage devices accessible to the system 506 and which may be executed by the processing unit(s) 508.

The processing unit(s) 508 including the switch instructions 504 and integrated circuit with configurable logic block(s) 502 may be implemented using examples of integrated circuits described herein, such as with reference to FIGS. 1-4. The processing unit(s) 508 may be implemented, for example, using one or more FPGAs, DSPs, ASICs, and/or SOCs. Other circuitry may be included in processing unit(s) 508 other than the switch instructions 504 and integrated circuit with configurable logic block(s) 502 in some examples. Application(s) 512 may be provided to implement any of a variety of functionalities, such as but not limited to, wireless, video/codec, and/or machine learning applications. An instruction generator 514 may be provided in some examples which may generate switch instructions 504 in cooperation with the application(s) 512 and/or operating system 510. For example, based on operations which may be desirable in executing the application(s) 512, the instruction generator 514 may generate switch instructions 504 that may cause the integrated circuit with configurable logic block(s) 502 to perform certain functionality (e.g. inverse square root operation). If a different application is performed, the instruction generator 514 may generate different switch instructions 504 which may cause the integrated circuit with configurable logic block(s) 502 to perform a different functionality. In this manner, same hardware may be used to perform different functionality as described herein in accordance with switch instructions.

While instruction generator 514 is shown in FIG. 5, it may not be present in other examples. In some examples switch instructions 504 may be pre-coded and or a library of switch instructions may be stored for different scenarios. However, in some examples instruction generator 514, may be provided to generate switch instructions 504 based on the application(s) 512 to be executed by the system 506. The instruction generator 514 may be implemented, for example, as a portion of a compiler or other executable instructions (e.g. software).

From the foregoing it will be appreciated that, although specific embodiments of the present disclosure have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the present disclosure. 

What is claimed is:
 1. An apparatus comprising: a plurality of configurable logic units; a plurality of switches, each switch coupled to at least one configurable logic unit of the plurality of configurable logic units; an instruction register configured to provide respective switch instructions to each switch based partly on a computation mode selection indicating a number of iterations to be performed through the plurality of configurable logic units for each switch for a computation; and a feedback line configured to, while iterating for the number of iterations specified in the respective switch instructions, provide an intermediate processing result from a final configurable logic unit of a routing path to an initial configurable logic unit of the routing path for the computation.
 2. The apparatus of claim 1, wherein the plurality of switches comprises a first switch and a second switch, and wherein at least one output of the second switch is coupled to an input of the first switch.
 3. The apparatus of claim 1, wherein the plurality of configurable logic units comprises an arithmetic logic unit, a multiplier-accumulator unit, a bit-manipulation unit, or combinations thereof.
 4. The apparatus of claim 1, wherein the respective switch instructions include selection signals that are provided to the plurality of switches to specify inputs and outputs of respective switches to be activated for the computation.
 5. The apparatus of claim 1, wherein the respective switch instructions comprise: allocating a portion of the plurality of configurable logic units to perform the computation based on an availability status of each of the portion of the plurality of configurable logic units; and reallocating the portion of the plurality of configurable logic units and re-determining a routing path during an operation in-process.
 6. The apparatus of claim 5, wherein allocating the portion of the plurality of configurable logic units to perform the computation comprises: configuring at least one of the portion of plurality of configurable logic units to perform at least one sub-computation of the computation to be implemented among the plurality of configurable logic units.
 7. The apparatus of claim 5, wherein the respective switch instructions further comprise: determining the routing path among the portion of the plurality of configurable logic units and the plurality of switches based on the availability status of each of the portion of the plurality of configurable logic units.
 8. The apparatus of claim 1, wherein the computation to be implemented comprises an inverse square root computation, a Galois-Field computation, or combinations thereof.
 9. The apparatus of claim 1, further comprising: an interconnect coupled to the plurality of configurable logic units, wherein the instruction register is configured to receive, from the interconnect, the computation mode selection.
 10. A method comprising: providing respective switch instructions to a plurality of switches based partly on a computation mode selection including a number of iterations to be performed through a plurality of configurable logic units coupled to the plurality of switches to perform a computation; activating respective inputs and outputs of the plurality of switches based on the respective switch instructions to perform the computation; iterating for the number of iterations; and while iterating for the number of iterations, providing an intermediate processing result from a final configurable logic unit of the plurality of configurable logic units of a routing path to an initial configurable logic unit of the plurality of configurable logic units of the routing path via a feedback line.
 11. The method of claim 10, further comprising receiving the computation mode selection indicating the computation to be implemented among the plurality of configurable logic units.
 12. The method of claim 10, wherein activating the respective inputs and outputs of the plurality of switches based on the respective switch instructions comprises: allocating a portion of the plurality of configurable logic units to perform the computation based on a respective availability status of each configurable logic unit to be implemented among the plurality of configurable logic units; and reallocating the portion of the plurality of configurable logic units, based at least on the respective availability status of each configurable logic unit, to perform another portion of the computation.
 13. The method of claim 12, wherein allocating the portion of the plurality of configurable logic units to perform the computation comprises: configuring at least one of the portion of the plurality of configurable logic units to perform at least one sub-computation of the computation to be implemented among the plurality of configurable logic units.
 14. The method of claim 12, further comprising: determining the routing path among the portion of the plurality of configurable logic units and the plurality of switches.
 15. An apparatus comprising: a plurality of configurable logic units; a feedback line coupled between an initial configurable logic unit and a final configurable logic unit of the plurality of configurable logic units; a switch coupled to at least a subset of the plurality of configurable logic units; and an instruction register configured to: receive a computation mode selection indicative of a computation to be implemented in at least the subset of the plurality of configurable logic units; and provide switch instructions to the switch based partly on the computation mode selection, wherein the computation mode selection includes a number of iterations to be performed through at least the subset of the plurality of configurable logic units, wherein, while iterating for the number of iterations, the feedback line is configured to provide an intermediate processing result from the final configurable logic unit to the initial configurable logic unit for the computation.
 16. The apparatus of claim 15, wherein the switch instructions include instructions to: allocate the plurality of configurable logic units to perform the computation based on an availability status of each of the plurality of configurable logic units to perform a portion of the computation; and reallocate the plurality of configurable logic units, based at least on the availability status of each of the plurality of configurable logic units, to further perform another portion of the computation.
 17. The apparatus of claim 16, wherein the switch instructions further include instructions to: determine a routing path among the plurality of configurable logic units and a plurality of switches based on an availability status of each of the plurality of configurable logic units to perform a portion of the computation. 